Slide rule



Sept- 21 1943. 1. RoBER-Ts 2,449,954

n SLIDE RULE Filed March 26, 1945 2 sheets-sheet 1 Sept. 21, 1948. l. s.ROBERTS 2,449,954

I SLIDE RULE Filedrmaroh 2e. 1945 2 sheets-sheet 2 Patented Sept. 2.1,1948 UNITED STATES PATENT OFFICE SLIDE RULE Ingham S. Roberts; RidleyPark, Pa. Y Application March 26, 19145, Serial No. 584,813

This invention relates to slide rules and is par- 4` ticularly concernedwith the mounting and guidance of the slidable member of such a rule.

It is well known that the ease, speed andaccuralcy with which a slider-ule can be operated depend upon the amount and uniformity of the forcerequired to move the slide. If this force is too great or too variable,the slide is diicult to set; if the frictional resistance to motion ofthe slide is too small, there is danger of an error due to failure ofthe slide to hold its position after being set. l-Ieretofore, the amountand uniformity of slide resistance to motion in slide rules have beenregulated frictionally by various methods, as for example: by accuratelyforming a snugv nt between the slide and the frame, or by slightlyspringing the slide or the sides of the frame so that the force whichneutralizes this springing increases the sliding friction, or as avariant of this method, springing the web of the frame below the slideso that the slide is lightly clamped by the sides of the frame, or bysupplemental means such as special springs for imposing a frictionalresistance to motion upon the slide, or adjustable means for varying thefrictional resistance by moving and setting one side of the framerelative to the other or adjusting the force of the spring or springswhich are employed to control friction. All of these methods havedisadvantages. It is expensive to manufacture and difficult to adjustsuch instruments to secure the best results from frictional resistance;even with careful manufacture the friction usually varies with theposition of the slide in the frame kand it deiinitely varies withchanges in atmospheric humidity and also by reason of wear of theinstrument itself. Even lunder the bestvconditions there is a smallamount of friction between the slide and the frame which is provided inorder to prevent errors due to slipping, and even thisk small amount isobjectionable in that it increases the diilculty of quickly andaccurately setting the slide. f

It is therefore an object of this invention to provide a new andimproved slide rule in which thekslide is arranged for substantiallyfriotionless motion in obtaining any setting thereof but in which meansis provided for iirmly holding the slide against movement at othertimes.

Another object of the invention is to provide a new and improved sliderule in which the main frame or body is formed with a guideway for theslide member, said guideway comprising portions which normally exert africtional grip upon the slide but which are yieldingly held in gripping2 position and are instantly releasable to permit free adjustment of theslide.

It isalso an object of the invention to provide a new and improved sliderule having guideways for the slide and'in which at least one of theguideways is yieldingly held in position to grip the slide memberfrictionally but is so mounted that a slight pressure applied externallyto the frame or body of the rule will release the frictional grip toallow free movement of the slide.

Other objects and advantages of the invention will appear from thefollowing description of several forms or embodiments of the inventiontaken in connection with the accompanying drawings illustrating thesame, in which:

Fig. 1 is a fragmentary perspective view of a slide rule embodying theinvention taken partly in transverse section and showing the slide asnormally held frietionally atvany adjusted position;

lFig. 2 is a transverse section similar to the sectional portion of Fig.1 showing the frame or body portion of the slide rule with the parts inthe relative positions assumed when the slide is removed; K

Fig. 3 is a transverse section showing in somewhat exaggerated fashionthe position assumed by the parts for release of the frictional grip ofthe guideways te permit free movement of the slide;

Fig. 4 is a detail perspective View partly in section showing a fragmentof the spring member employed to connect the guide portions of the sliderule shown in' Figs. 1, 2, and 3;

Fig. 5 is a transverse sectional view of a slide rule in which theresilience of the frame or body portion provides the yielding characterof the guideway;

Fig. 6 is a transverse` section showing another modification in whichtwo portions of the guidewayare connected by a spring member on whichthe rule rests in normal position;

Fig. 7 is a transverse section of a further modification in which thematerial of the frame or body provides a yielding connection betweenportions of the guideway and having a specially formed base tofacilitate release of the slide;

Fig. 8 is a transverse sectional view showing another form of theinvention in which one side of the guideway for the slide is formed oftwo parts connected by av spring member Fig. 9 is a transverse sectionalView of a further modiilcation in whichr the material of the baseprovides the yielding connection between two portions of the guideway atone side of the slide; f-

Fig. is a transverse section of a slide rule of the double-faced type,showing a construction similar to that of Fig. 8 applied thereto;

Fig. 11 is a transverse section of a slide rule of the double-facedtype, showing an arrangement similar to that of Fig. 9;

Fig. 12 is a fragmentary perspective detail showing a modification ofFig. 10.

In Figs. l to 9 the invention'. is `illustrated as applied to.the-Mannheim type of Aslidel rule in which the graduations of the fixedmember are on the upper surface of said member which is designed to lieupon the surface of a desk or table when in use; the slide is usuallygraduated on both faces and is reversible in the fixed member. As shownin Fig. 1, the frame or body I6 includes a base I2 with a guide portion`I4 substantially rigid therewith and a second guide portionY I6` whichis connected to the part I4 by a spring member I6. As seen in Fig. 4,the spring member includes a flexible andresi'lient web portion 20 withflanges 22 disposedsubstantially at right' angles to the weband-'formed'withv lips 24 at their free edges. It may'be assumed thatthe parts I2, I4, and I6 are moulded preferably of synthetic plasticmaterial in which'the spring member VI 8 can be imbedded during themoulding process so that its flanges 22 will be firmly and permanentlysecured in the parts I4 'andI6 with the lips 24 and perforations 26serving .to perfect this anchorage. The portionof the web 2l! vwhich isleft exposed may have "a normallyat form as seen in Fig. 2 inwhichthe'guideway'grooves 28, 28 in the parts I4 and' I6 respectivelyare shown open toward `each other ready'to receive the slide 30.

Insertion of the slide member -36 vwith its `guide tongues '32 enteredin thegrooves 28, forces' the parts I4 and I6 into the position shown inFig. 1 in which their upper and graduated surfaces lie in a common planewith the Aupper surfaceof the slide member 36 while the 'web 2Ii'of thespring connector I8 is slightly flexed.' This change in relativeposition of the guide members `I4 and I6 increases the distance betweentheir guideways 23,28 so that the spring member I8 vreacts withsuflicient force to cause the slide 36 Hto be fric-y tionally grippedbetween the parts I4 and I6; thus it is held firmly at any adjustedposition.

With the top surfaces'of the parts I4, I6 and 86 in a common plane,guidemember I'6 is spaced above the base portion IZ of the frame and isheld yieldingly in this position by the spring I8. To release thefrictional hold 'of the parts 'I4 and I6 upon the slide 38 Vit isonly'necessary to'depress the member I6 slightly. This causes the web 28of the spring member I8 to be flexed to a greater degree than in itsholding position as shown in Fig. 1 so as to increase the distancebetween the guide grooves 28, 28. Fig. 3 illustrates this action butshows the member I6 depressed much farther than necessary forv merelyreleasing the frictional grip ofthe guide grooves 28, 28 upon the tongueportions 32, 32 of. theslide 36, the release movement being exaggeratedinthis view merely to clarify the effect of such an adjustment of thepart I6. Inpractice, avery slight downward movement of the'member.I6.from its posiA tion shown in Fig. lwill be sufli'cient toirelieve thepressure normally exerted upon the slide30`and permit it to be freelyadjusted. 'When theslide has been moved to thedesired position, thefingerpressure on the part I6 -is removed alloWdng-it 'to spring intogripping position so as to hold the 4 slide 38 firmly until anotheradjustment is to be made.

Fig. 5 shows a slightly modified construction in which the frame or body40 includes a base portion 42 and an integral guide portion 44. Theopposite guide portion 46 also is integral with the frame, beingconnected to the part 44 by a relatively thin web 48 which functions inmuch the same manner as the spring I3 of Fig. i. It may be understoodthat this structure will also be moulded of plastic material and that inthe original moulding operation the part 48 will be given a position inwhich it is somewhat divergent from the part 42. Then when the slidemember 5D is inserted with its guide tongues 52 engaging in the guidegrooves 54, the web 48 will be sprung into the position shown in Fig. 5and will react to provide the desired friction for gripping the slide 50at adjusted position. The clearance space 56 between the portion 46 andthe base 42 will permit the part 46 to be slightly depressed Wheneverthe slide 50 is to be released for adjustment to a new position In Fig.6 the slide member 6o is shown gripped between guide members 62 and 64which are con.- nected by one or more spring members 66 to form theframe or body of the rule. This construction may be made of wood ifdesired; that is, it is not necessarily moulded of plastic material. Thespring element 56 will be initially made with its wing portions 68, 68disposed in planes somewhat oblique to each other so that when theseportions are Vbrought into a common plane by insertion of the slide 68as shown in Fig. 6, the spring will react to pinch the slide 60 betweenthe guide surfaces 12 and 'i4 of the parts 62 and 64 respectively. TheWing portions 68 of the spring member 66 are shown secured to parts 62and 64 by means of screws 16, but if preferred it will be recognizedthat these wing portions might be moulded in the parts 62 and 64 if thelatter were made-ofv plastic material.

The middle portion 'I8 of the spring 66 is bent downward slightly belowthe plane of the bottom surfaces 62a and 64a. of the parts 62 and 64 sothat when the slide rule rests upon a fiat surface as indicated by thebroken line Ain Fig. 6, a kslight pressure upon the upper faces of theparts 62 and 64 will flex the spring G6 upon its depressed portion 'I8as a fulcrum and will thus separate the guide surfaces 'I2 and 'I4 so asto relieve their frictional grip on the slide member 6B and permit freeadjustment of the slide. Release of the finger pressure on the parts 62and 64 instantly restores the parts to gripping position to maintainadjustment of the slide 60.

Fig. 7 shows a one-piece frame 86 adapted to function in the same manneras the structure shown in Fig. 6. The frame includes guide portions 82and 84 having guide grooves 85, 86 which engage the tongue portions 88of the slide member 90. The web 92 which forms the middle portion of thebase of the frame is relatively thin and the bottom of the frameincludes a flat surface 94 on which the rule normally will restandfavsurface 96 disposed at a slight angle to the plane of the surface94 so that simultaneous pressure upon the upper portions 82 and 84 willtend to flex the thin portion 82 of the base and separate the guidegrooves 85, 86 sufiiciently to release the frictionally held slidemember EIB. In this form, as in the case of that shown in Fig. 5, theportion 92 will be initially moulded with the surface 86 at a 'greaterangle to the plane of the surface 94 so that insertion of the slideserves to spread thefparts82 and 84 and produce: a stress in theAthinweb 92 resulting in the rfrictional gripping of` the slide 90between the guide portions 82 and 84. y f

Fig. 8 illustrates a somewhat different application of the principle ofthe invention. in this construction the base |60 Iincludes a guidegroove |02 which provides a permanent running fit for the tongue |04 ofthe slide member |06. The 0pposite tongue |08 of the slide isengagedbetween the guide surface I I formed in the base member |00 and theguide surface |I2 formed in a separate member II4. The member ||4 isconnected to the base member |00 by a resilient channelshaped member II6 which may be of spring metal or other suitable material and which hasanchorage anges I I8 so that it may be permanently secured in th-e basemember |00 and in the member ||4 when these parts are moulded,preferably of plasticmateral. The initial form of the spring member ||6will be such that the tongue |08 is frictionally gripped between thesurfaces |I0 land ||2 but to release this hold the part ||4 may berocked slightly by pressure upon its outer edge |I4a, thus tilting thesurface I|2 outwardly just enough to permit the slide |06 to be movedfreely as desired. Removal of the pressure at I |4a will cause thespring |16 to return the part II4 to gripping position. l

In Fig. 9 the Ibase |20 of the slide rule is provided with a tongue |22serving as one side of the guideway for the slide |24 and the slideitself has a groove |:26 dimensioned as a permanent running t for thetongue |22. The groove I 28 at the opposite side of the slide |24 isoccupied by the tongue |30 of the base member |20 and the tongue |32 ofan integral portion |34 which is attached to the base by a part |36 ofrelatively thin cross section extending throughout the length of therule.l A clearance space |38 between the base |20 and the portion |34permits the part |34 to be depressed to relievethe frictional grip ofits tongue |32 against the side of the groove |28 in the slide, suchdepression of the part |34 being permitted by the resilience` of thematerial in the web |36. In this case, the pressure will be applied tothe edge of the part |34 adjacent the slide |24 instead of at the outer-edge as in Fig; 8.

Fig. shows a construction quite similar to that of Fig. 8 for applyingthe same principle to a slide rule of the double-faced type. In such arule the slide member is mounted between guide members and the guidemembers are connected at their ends by plates riveted thereto andoverlapping the upper and lower faces of the slide and the guides.

Fig. 10 shows the slide member |40 with one of the guide members at |42and with the connecting plates |44.v The opposite guide member consistsof two parts |46 and |48 respectively which are separated by a space |58and -connected by a spring channel member |52 similar to the member ||6of Fig. 8. The part |42 has a slot |54 formed as a running nt for thetongue |56 of the slide |40, while the tongue |58 of the slide Iisgripped between the parts |46 and 48. However, these parts may beslightly separated by pinching their outer edges together or toward eachother andthus flexing the connecting element |52 so aste release themember |40 for sliding adjustment. To permit the resulting rockingmovement of the parts |46 and |48 the plates |44 may be formed withclearance notches as shown at |45 adjacent theinner edgesof said partsof the two-part guide member.

The rule shown in Fig. 11 kembodies the prima ple of Fig. 9 as appliedto the double-faced rule and includes a slide member |60 carried betweenguide members |62 and |64 which are tied together in the Vusual way byplates |66. The member |62 includes a tongue |68 formed as a running fitin the groove |10 of the slide |60. The opposite groove |1-2 engages asplit tongue formed on the guide member |64. The tongue is 4split byreason of a slot |14 and extending longitudinally in the member |64together with a communication channel |16 which provides a portion |18of rel.- atively thin cross section opposite Ithe inner end of the slot|14. Initially, the part |64 will be moulded with the walls of the slot|14 diverging so that when the rule is assembled the two parts |86 and|82 of the tongue which fits the groove |12 will be sprung slightly tofit the groove and will exert sufficient friction against the slidewalls thereof to hold the slide |60 at adjusted position. This frictionmay .be relieved by pinching the part |64 adjacent the edges of theslide |60, thus disengaging the tongue portions and |82 from the sidesof the groove |12.

It may be understood that in Figs. 8, 9, l0, and 11 the clearancebetween the tongue-and-groove features at the right side of each figureis greatly exaggerated and is intended to indicate merely a free runningt since there is no adjustment between the tongue and groove at thisside of the slide rule.

It may be further noted that in the other forms of the invention shownin Figs. 1 to 7 inclusive, in which the slide is rel-eased by a tiltingof one of the guide members as it separates from the other guide, thetongues formed on each of the slide members have outwardly convergingside walls and the grooves of the guideways have outwardly divergingside walls to prevent any binding between the tongue-and-groove featuresby reason of the change in angular position of the movable guideway.This is true of all the forms except that shown in Fig. 6 and, actually,the same principle is involved in that structure; in this ease the natbottom wall of the slide serves as a guide surface adjacent each lateralledge of the slide. These bottom surfaces of the slide ride upon ilatguideway surfaces which lie in a common horizontal plane and whichcooperate with the sur- 'faces 12 and 14 which extend at acute angles tothe bottom guide surfaces. Thus each guideway has outwardly divergentguide surfaces and the cooperating guide surfaces of the slide areoutwardly convergent like the guide tongues o-f the slides shown in theother figures. In all these forms, therefore, the slightest separationof the two guide portions of the fixed scale member relleves thetapering guide surfaces of the slide lfrom the divergent guide groovesof the iixed members and prevents the binding which would result if ythetongues were formed with parallel guide faces like those of Figs. 8 to11.

In the construction shown in Figs. 10 and 1l instead of requiring anyplay between the rivets of the end plates and the rockable parts |48 and|18 a slightly different arrangement may be employed as indicated inFig. 12, which is a modification of the structure of Fig. 10. The upperpart of the two-piece guide member is shown at I48a with its end portion|481) cut free and clamped firmly under the upper plate |44 with a ller|48 interposed between the portion |48?) and the lower part |46. Thisleaves the part 48a connected to the part |46 only by the element |52and thus permits it to be rockably adjusted for amasse- 7. releasing.the slide i411. The guideway infith'e xed endy portion |48?) is madewith enough clear'-Y ance to insure easy operation. It will be evidentthatA the same type of construction. can be employed for the form ofthe' invention shown in Fig.V l1 instead of relying upon any clearancebetween. the parts H8 and |64 and the rivets by which the plates |66 aresecured thereto.

It will be seen that an incidental advantage' of my invention is thatnearly all the forms thereof which are herein shown and described may beoperated with one hand if desired, leaving the oth'er hand free forholding a magnifying glass when securing a very accurate setting or fornoting the computations which are made with th'e aid of the rule. Ifthus used the. rule will lie on the desk or table and the xed memberwill bev held in position with one or two fingers or with the base ofthe palm so that the necessary slight pressure can be exerted forreleasing th'e slide. The slide can th'en be manipulated by'orie lingerofV the' same hand.

In` the gures of the drawing' the usual transparent slider which ismovably' mounted' on the xed member of theV rule hasV been. omitted;` itwillw beunderstood that the sliderwill have suiii'- cient play invitsguideway and Will'have a take-up spring of: suilicient range topermit of theA slight movements of oneside of' the iixed member requiredfor releasing the slide in accordance with' this invention. It may alsobe noted that in the forms shown in Figs. lO and 1'1 the rivets whichconnect theplates |44' and |66 of these forms respectivelywill have alvery" slight amount of play in the two-part guide portions through whichthey'pass' so `as to permit the slight rocking'movements of the partsrequired for releasing.v the Slide'.

While there is shown and described herein certain structurev embodyingthe invention; it is to be understood that the invention is not limitedtheretoor thereby but may assume numerous other forms and includes` allmodifications, variations and equivalents coming` within the`scopeofthefollowing claims.

I- claim:

1f. A slide rule comprising a slide and a xed scale member'whichcomprises abase portion with' a xed guideway formed thereon for one sideo'f` the slide; a movable guideway for the opposite side-of` the slide,said base portion extending beneath the movable guideway, and aLflexible resilient support extending from th'et fixed guideway andcarrying the movable guideway normally spaced above thebase and normallyin fri-ctional engagement withA the slide, whereby fiexure.' of saidsupport toward the base swingsi saidA movable guideway away'from theflxedguideway,r releasing tl'ie slide foriree movementbetween them;

2.` A' slide rule comprisingia slide, a'fixedsc'ale member'whichcomprises a pair 'of opposed guide- Ways for the slide, means. rigidwith one of said' guideways and forming a base underlying the secondguideway' and' ileXible and` resilient means'. normally holdingsaid'guideways in'frictionalengagement with'theA slide, sai'd'basevforming means providinga ulcrum so that s'aid'se'cond'guidev/ay isseparable from' the slide by= a substantially arcuaternovement whichwithdraws its guide surface from. the cooperating surface of the slide,leaving said surfaces spaced apart topermitlf'ree movement of theslidewith respect`to=the xed scalemember.

3; A' slide rule' comprising a slideand4 aiixedl4 the' slide, a-'movable`gui'deway for the' oppositeY side ofrthe slide-Sandraflexiblezresilient supporte way,.ireieasing' the' slide for free movementbetweeny them'.

4'. A slide rulef comprisinga-slide, anxedf scalemember'whielrcomprises' a-pair or opposed guideways fori'the; slide;means rigid' withy one oi' said gui'deways and. forming. a baseunderlyi-xigthe second guideway, and flexible resilient me'ans in`terconnectingsaidguidew-ays below' the slide: andi holdingz themnormally iri frictional engagement therewith releasable byy fi'exure ofsaidf resilient connection, said slidev and g'uide'way'sf hea/ingv in@ter-engaging portions shaped soas' to separate freely' upon' such:ilexure ofthe resilient connec- 'cion'.

5;- A- slide rule'- comprising: a slide and a fixed' 25, scale memberwhich includes a. fixed guideway forone sidefof the slide-'andaitwoepart guidew'ay for the other side of the slidefthe sli'de and saidtwo-part guideway' having interenga'ging tongue-l and-groove guidemeans, the gui'de` means ofthe" two-part guid'eway having: al pair' o!oppositeiy facing guidev surfaces x'iorrn'al-ly inffriction'al con-`tact with cooperatingzsurfaces of. th'e slide', and' a resilientconnection at a distance from said' guide surfaces adaptedrtofbefiexedto' alterithe' distance 35; between sald'surface's; therebyreleasing'. the slide for free movement-relativer to: .the fixed scale'member.

6l Arsli'derule comprising Va slide' and" a ii'xed' scale member which'includes afixed guidewayffor one sidef-of thefsiideand aitwo-'partguideway for' the other side? of the slide, the slide having' a tongue,and` seid` two-partv guideway" forming agroove' for said tongue withoppositeiy facing guide;

surfaces normallyf in= frictional: contact with the tongue, the.two-p`art guidewayf including a re;-

silientf4 conneotionfat aA distance` from the guide; surfaces-"of theIgroove adapted' to be 'exd to alter thewidth of th'egroove and' therebyrelease the sliderfor free movement relative to the liked scale member.

7-. A- slide rulecomprising a slide and' a fixed scalemember whichincludes-a fixed guideway for one-side'of the s-lidoandfatwo-partguidewayfor" they otherside.` of. the: slide; the slide having' agroove.. and .saidtwoepart guideway comprisingi a. tongue havingoppositeiy facing guideI surfaces normally in: friction'al contact withopposite sides ofthe groove; and a` resilient connection betweenthevtwo. parts* of-'said tongue atfa distance'v fromits saidguidelsurfaces and adaptedv toy be exed to alter the: distanceV` between saidsurfaces, re`

duoing the widthof' the? tongue. and releasing th'e slide for freemovementwrelative to th'exedscale' member;

twoepart guidewayfhaviriglinterengaging ton'gue-4 and-groove guide'means', and thegiiideway'comprisin'gE anupper parts and allgiwer` partconnected bi a vertically extendingile'xibley and resilient web normallyholding said tongue-andlgrooveA guide meansk infrictio'nal engagementbut yieldable when prefssr'islsppliedtosaid upper partto alter th'edistance between opposite surfaces of one of the guide means to releasethe slide for free movement relative to the fixed scale member.

9. A slide rule comprising a slide and a xed scale member which includesa fixed guideway for one side of the slide and a two-part guideway forthe other side of the slide, the slide in said two-part guideway havinginterengaging tongueand-groove guide means, said two-part guidewaycomprising an upper part and a lower part spaced apart and connected bya vertically extending flexible and resilient web upon which the upperDart is tiltable at will with' respect to the lower part to release theguide means of the slide,

10. A slide rule comprising a slide and a xed scale member whichincludes a base portion with a iixed guideway formed thereon for oneside of the slide, a movable guideway for the opposite side of theslide, and a exible resilient support extending from the xed guidewayand carrying the movable guideway normally spaced above the base andnormally in frictional engagement with the slide, th'e slide andguideways having interengaging tongue-and-groove guide means in whichthe side walls of the grooves are outwardly divergent and the side wallsof the tongues are outwardly convergent to insure free separation ofsaid guide, whereby exure of said support toward the base swings themovable guideway away from the fixed guideway, releasing the slide forfree movement between them.

11. A slide rule comprising a slide and a xed scale member which'comprises a base portion with a fixed guideway formed thereon for oneside of the slide, said xed guideway including upper and lower surfacesfixedly spaced from each other and adapted to engage respectively theupper and lower edges of a slide, a movable guideway for the oppositeside of the slide, said base portion extending beneath a movableguideway, exible means connecting said movable guideway normally spacedabove the base and normally in frictional engagement with' the slidewhereby flexure of said support swings the movable guideway away fromengagement with said slide, releasing the slide for free movementbetween them,

f said resilient support constituting the sole resilient meansincorporated in said xed scale member.

INGHAM S. ROBERTS.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,329,902 Hemmi Feb. 3I 19201,790,569 Asper 1 Jan. 27, 1931 FOREIGN PATENTS Number Country Date226,773 Germany Oct. 7, 1910 468,323 Great Britain July 2, 1937

